Grohe Geneva Thermostat not hot enough

Discussion in 'Shower & Bathtub Forum & Blog' started by rchrdprss, Dec 21, 2008.

  1. rchrdprss

    rchrdprss New Member

    Messages:
    2
    We have a Grohe Geneva Thermostat model, 19 616 as a mixing valve with a separate flow control valve in our shower. The temperature setting on our water heater is set to about 140. The hot water coming from all of the sinks is very hot.

    The temp in the shower is only warm even when set to the hottest possible setting. This is a single handle adjustment valve. There is an adjustment on the valve to set the mix temperature. However, even at the highest setting the water coming out is not as hot as the water coming from the sink hot water valve. I assume that this is some maximum high temperature setting internal to the valve.

    Right now I have the valve set so that there is practically no cold setting at all. That is, when you set it to 100, and turn it down to 70, the temp does not change. That means that the adjustment lever is pulled fully off of the adjustment diaphragm. In reality I have only full hot water. BUT. we can not get the water as hot as we like.

    How can I fix this so I get water as hot as from the faucet at the sink?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,262
    Location:
    New England
    the real question to me is when adjusted so the dial is reading a value, is the output correct?0the range is nomally more than adequate. It may need replacement.
  3. rchrdprss

    rchrdprss New Member

    Messages:
    2
    The hot water at the tap 4 or 5 feet from the shower is approx 133F. The shower temp control has an adjustment range of 70 to 110, than an indent and than marked F. I presume F means Full.
    It is currently set very nearly to those values. That is, 70 is about 70, 80 is about 80, 100 is about 100 and so forth. My problem is that the absolute max temp is around 115F.

    I can adjust the range so that when set to 70 it really outputs 100, when set to 80, it outputs 110, and when set to 110, it outputs 115. I can adjust it so that when set to 70 it outputs 115, and any higher setting is still 115. With the adjustment hardware removed, it stays at the max of 115, or so.

    What I want is to be able to get it to output 120, and 125, and 133. But it does not. It seems almost as if the internal thermostat is set to 115. How can I make this give me hotter water? Better yet, can I rebuild it so as to mix simply hot and cold, so that I can have full cold, or full hot, or anything in between and forget the pressure control.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,262
    Location:
    New England
    Unless you are showering in an unheated room or the head it waaaay up there, it would be very unusual to want water that hot coming out. Not knowing the internals of that valve, my guess is that they purposely limited it to the range listed. The max listed on the valve is (from what you indicated) 115-degrees, and if it is 115 when it is adjusted to that, you need a different valve if you really want it hotter. A pressure-balanced valve only has a mechanical limit stop, and you would probably be able to set it high enough to get full hot.
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